A typical electronic watthour meter for measuring electric energy consumption requires resetting of the demand function after periodic reading of the meter, such as every month. The reset is typically accomplished by activating a reset switch located within the meter housing by depressing a plunger connected to the switch and extending through an opening in the housing. For example, an early prototype version of the General Electric EVX meter produced by the assignee of the present invention, included a plunger carried by the housing. The plunger, once rotated 90.degree. to an activate position, could be depressed by the technician to activate the reset switch positioned within the meter housing to thereby reset the meter.
Tampering with the reset plunger is typically discouraged by the provision of a switch cover or latch cover for the plunger. The switch cover is typically pivotally connected to the meter housing and is movable between open and closed positions. In the open position, the plunger may be rotated and depressed to reset the meter. In the closed position, activation of the plunger is not possible, since the plunger cannot be rotated or depressed. Moreover, the switch cover typically allows for a wire, band or padlock seal to be used to secure the switch cover in the closed position.
An early prototype EVX meter, for example, included a plunger having a thumbgrip portion which permitted the technician to grasp and then rotate the plunger. The thumbgrip portion included a circular opening in communication with a slotted opening thereby permitting insertion of either a padlock or tape seal. The latch cover of this early prototype meter had a rectangular cutout roughly aligned with the openings in the plunger. Accordingly, a seal or padlock would retain the latch cover in the closed position and prevent operation of the plunger. Unfortunately, the padlock or seal of the early EVX meter was supported only by the thumbgrip portion of the plunger. Accordingly, the plunger could be damaged by manipulation of the seal or padlock thereby requiring replacement of the plunger.
The switch cover of the early EVX meter was snapped in place on a hinge pin integrally molded into the housing or meter cover. In addition, an external bump was molded on an outer portion of the switch cover to attempt to provide means for holding the latch cover in the open position when the plunger was accessed by a technician. The convenience of the technician is enhanced if the cover may be secured in the open position. Unfortunately, the early EVX meter cover latch did not provide the desired positive locking in the open position. Moreover, the typical plastic materials used for a meter housing and for the associated switch cover and hinge pin may be susceptible to both molded-in stresses and stresses produced during operation. These stresses are amplified particularly in the presence of notches, nicks, cuts, etc. Environmental influences may also degrade the typical polycarbonate plastic material and may lead to a failure of the switch cover to remain in the open position.
Another disadvantage of the early EVX meter resulted from the hinge portion of the switch cover defining an exposed opening for moisture and dirt to enter into the area between the hinge pin and hinge portion. Accordingly, the long term reliability of the hinge may suffer.